The bike is an F3 actually, but with an F2 engine. The battery ran flat so I charged it up and measured voltage and it’s not charging at all, same voltage with the bike off and on at any rpm. I did the resistance check on rectifier and stator and both seem to be in spec. Rectifier seems to be aftermarket or from a different bike, definitely not a stock one. Is there any other tests that can be done to narrow down the problem to a specific part?